A wedge-shaped motor mount is known having two symmetrically arranged elastomeric bodies which are vertically stressed both in shear and pressure and are bonded between inner and outer metal parts. Depending on the angle of inclination of the wedges it is possible to produce different spring constants. Simultaneous existence of both shear and compressive forces avoids bending stresses and gives very good force distribution in the spring element. However if lifting forces are applied to such a spring element the elastomeric material is tensioned and quickly either detaches itself from the metal elements to which it is bonded or rips. It is known to avoid this difficulty by providing such plates which are stressed by pressure. However when such an arrangement is used the vibration- and noise-damping characteristics of the spring are substantially impaired. Thus such wedge-shaped mounts cannot be used wherever lifting forces might be encountered.
It has also been suggested to arrange two such wedge-shaped mounts asymmetrically and if necessary to also prestress them against eachother. Such arrangements however almost completely eliminate the noise-damping characteristics of the spring and creates a bulky assembly. In addition the mounting of such devices and the determination of just the right materials for the desired spring constant becomes very difficult.
In modern motor vehicles the engine is of substantially greater power output per unit of weight than ever. Thus the vertical stresses to which an engine mount are subjected remain the same while the reaction forces caused by the engine torque have grown considerably. These reaction forces are determinative of the service life of elastic motor mounts. It is impossible to use in modern automotive vehicles having such high-power engine conventional motor mounts especially when the transmission is bolted directly to the vehicle engine as with front-wheel drive or a rear-mounted engine. Such mounts are also inadequate for separately mounted transmissions in which the reaction forces are equal to the difference between the input and output forces.